– 13 oz 320 g beef tenderloin, flank steak or flap meat, diced – 2 tablespoons olive oil divided – 2 cloves garlic sliced – 7 baby bella mushrooms remove the steams and quartered Marinade – 1 tablespoon reduced-sodium soy sauce – 1/2 tablespoon dark soy sauce – 1 tablespoon corn starch – 1/2 teaspoon baking soda Brown Sauce – 1 tablespoon soy sauce – 1 tablespoon oyster sauce – 1/2 teaspoon sugar – 1/2 tablespoon corn starch – 4 tablespoons water